1. Field of the Invention
The present invention relates to cooling systems, and more particularly, but not by way of limitation, to a cooling system incorporating flow coupling end caps for facilitating the flow-coupled stacking of low profile extrusions (LPE's).
2. History of Related Art
Many aspects of the technology of, and advances in, methods of and systems for cooling and heating utilizing heat pipes are well developed. A heat pipe is a device for transferring heat by means of the evaporation and condensing cycle of a heat transfer liquid enclosed in a casing from which noncondensable gasses have been removed. There are, of course, significant limitations on the amount of heat a heat pipe can transfer in a given time or in a given space even when the heat transfer liquid is pumped therethrough. In that regard, special configurations are often major design aspects in dealing with heat pipes and/or other forms of heating and/or cooling systems. In the present application, particular emphasis will be placed on heating systems, but the application of heating and/or cooling application is contemplated relative to discussions herein.
The need for thermal stabilization of electronic components is well recognized in industry today. In that regard, LPE cooling devices are extremely useful in printed circuit board (PCB) level cooling of electronic components, and for use as heat exchangers in applications where space is limited and/or low weight is critical. LPE refers to a heat exchange apparatus comprising an integral piece of metal having a series of micro extruded hollow tubes formed therein for containing a fluid. LPE's preferably have multi-void micro extruded tubes designed to operate under the pressures and temperatures required by modern environmentally safe refrigeration gases and to resist corrosion. Aspects of LPE's and their related applications in the industry are set forth and shown in the above-referenced co-pending U.S. patent application Ser. No. 09/328,183.
Low profile extrusions can currently be manufactured with a profile, or height, as low as about 0.05 inches and with tubes of varying inner diameters. Of course, future advances may allow such low profile extrusions to be manufactured with an even smaller profile. Such low profile extrusions have been conventionally used in heat exchanger applications in the automotive industry, and are commercially available in strip form (having a generally rectangular geometry) or coil form (a continuous strip coiled for efficient transport).
An example of a low profile extrusion is described in a brochure entitled “Thermalex, Inc.—Setting A Higher Standard in Aluminum Extrusions” (hereinafter the “Thermalex Brochure”) provides additional detail regarding the Thermalex low profile extrusions and is incorporated herein by reference.
U.S. Pat. No. 5,342,189 to Inamura, et al, which is incorporated herein by reference, provides additional detail regarding an extrusion die for making such low profile extrusions. The extrusion die is used for making multi-cavity flat aluminum tubes, which are used for small heat exchanger components, in automotive air-conditioners, condensers, and radiators. The insert die is composed of a male die section having a protrusion part and a female die section, having a die cavity, and is held detachably in a die holder. The male section is a roughly rectangular plate-shaped component, and has an integrally formed twist prevention region which is inserted into the receiver groove of the female section which is integrally formed thereon. The protrusion part defines the cavity shape of the multi-cavity flat tube, and the female section has the die cavity of the required cross sectional shape to define the outer shape of the tube.
U.S. Pat. No. 5,353,639 to Brookins, et al, which is incorporated herein by reference, provides additional detail regarding a method and apparatus for sizing a plurality of micro extruded tubes used in such low profile extrusions. As described by the Brookins patent, a predetermined number of micro extruded tubes are stacked on the base fence between the fixed side fence and the clamping fence. The internal webs of the tubes are aligned throughout the stack, perpendicular to the plane of the base fence. The clamping fence is moved toward the stack of tubes to prevent the stack from moving laterally. The die platen is moved toward the stack of tubes and the mating surface of the die platen is in mating engagement with a side surface of the uppermost tube in the stack. A predetermined amount of pressure is applied to the stack of tubes through the die platen. The pressure is applied equally across the entire side surface of the uppermost tube and is transmitted equally through all the tubes of the stack in the sizing die.
Other developments in cooling apparatus may be seen in U.S. Pat. No. 5,285,347 to Fox et al., which describes a hybrid cooling system for electrical components. A hybrid heat sink is specially adapted to transfer heat to two cooling fluids. This heat sink is incorporated into a cooling system in which some of the electronic components of an electronic device may be cooled by two cooling fluids and some electronic components may be cooled by one cooling fluid. The electronic components are mounted on a circuit board. In the Fox reference, one of the cooling fluids is air and one is a liquid. The hybrid heat sink is attached to electronic components that cannot be cooled to the normal operating range by the cooling air alone. The cooling air is caused to flow over the surface of the heat sink, removing some of the heat. In addition, the cooling liquid is caused to flow through the heat sink, thereby removing additional heat. In addition, U.S. Pat. No. 5,901,037 to Hamilton, et al. describes a system for closed loop liquid cooling for semiconductor RF amplifier modules. The system comprises a combination of a plurality of elongated microchannels connected between a pair of coolant manifolds for conducting liquid coolant beneath the transistors to dissipate the heat generated thereby. The system also includes a heat exchanger, a miniature circulating pump located on the module, and passive check valves having tapered passages for controlling the flow of coolant in the loop. The valve comprises a truncated pyramid-shaped microchannel valve having no moving parts and is fabricated so as to be a part of either the circulating pump assembly, the coolant manifold, or the microchannels.
It has been shown that the use of multiple layers of LPE's greatly improves the efficiency of the heat removal process. Furthermore, it is disclosed in the above-referenced co-pending U.S. application Ser. No. 10/328,537, U.S. application Ser. No. 09/328,183, U.S. application Ser. No. 10/328,438 and U.S. patent application Ser. No. 09/328,183, that heat pipes provide superior performance in a low-profile, light-weight package. Moreover, the stacking of a series of heat pipes provide superior performance in a low profile, light weight package. It would be an advantages therefore to provide a design incorporating a stacked array of liquid-loop LPE cooling systems, facilitating the circulation of the heat transfer fluid through a stacked liquid-loop system.